/* libpbm1.c - pbm utility library part 1
**
** Copyright (C) 1988 by Jef Poskanzer.
**
** Permission to use, copy, modify, and distribute this software and its
** documentation for any purpose and without fee is hereby granted, provided
** that the above copyright notice appear in all copies and that both that
** copyright notice and this permission notice appear in supporting
** documentation.  This software is provided "as is" without express or
** implied warranty.
*/

/* See pmfileio.c for the complicated explanation of this 32/64 bit file
   offset stuff.
*/
#define _FILE_OFFSET_BITS 64
#define _LARGE_FILES

#include <stdio.h>

#include "netpbm/pm_c_util.h"
#include "netpbm/mallocvar.h"
#include "netpbm/shhopt.h"

#include "libpbm.h"
#include "pbm.h"



bit *
pbm_allocrow(unsigned int const cols) {

    bit * bitrow;

    MALLOCARRAY(bitrow, cols);

    if (bitrow == NULL)
        pm_error("Unable to allocate space for a %u-column bit row", cols);

    return bitrow;
}



void
pbm_init(int *   const argcP,
         char ** const argv) {

    pm_proginit(argcP, (const char **)argv);
}



void
pbm_nextimage(FILE *file, int * const eofP) {
    pm_nextimage(file, eofP);
}



void
pbm_check(FILE *               const fileP,
          enum pm_check_type   const checkType,
          int                  const format,
          int                  const cols,
          int                  const rows,
          enum pm_check_code * const retvalP) {

    if (rows < 0)
        pm_error("Invalid number of rows passed to pbm_check(): %d", rows);
    if (cols < 0)
        pm_error("Invalid number of columns passed to pbm_check(): %d", cols);

    if (checkType != PM_CHECK_BASIC) {
        if (retvalP)
            *retvalP = PM_CHECK_UNKNOWN_TYPE;
    } else if (format != RPBM_FORMAT) {
        if (retvalP)
            *retvalP = PM_CHECK_UNCHECKABLE;
    } else {
        pm_filepos const bytesPerRow    = (cols+7)/8;
        pm_filepos const needRasterSize = rows * bytesPerRow;
        pm_check(fileP, checkType, needRasterSize, retvalP);
    }
}



void
pbm_validateComputableSize(unsigned int const cols,
                           unsigned int const rows) {
/*----------------------------------------------------------------------------
   Validate that the dimensions of the image are such that it can be
   processed in typical ways on this machine without worrying about
   overflows.  Note that in C, arithmetic is always modulus
   arithmetic, so if your values are too big, the result is not what
   you expect.  That failed expectation can be disastrous if you use
   it to allocate memory.

   See comments at 'validateComputableSize' in libpam.c for details on
   the purpose of these validations.
-----------------------------------------------------------------------------*/
    if (cols > INT_MAX - 10)
        pm_error("image width (%u) too large to be processed", cols);
    if (rows > INT_MAX - 10)
        pm_error("image height (%u) too large to be processed", rows);
}



static unsigned int
bitpop8(unsigned char const x) {
/*----------------------------------------------------------------------------
   Return the number of 1 bits in 'x'
-----------------------------------------------------------------------------*/
static unsigned int const p[256] = {
    0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
    1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
    2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6,
    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
    3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7,
    4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8 };

    return p[x];
}



static int
bitpop(const unsigned char * const packedRow,
       unsigned int          const cols,
       unsigned int          const offset) {
/*----------------------------------------------------------------------------
  Return the number of 1 bits in 'packedRow', ignoring 0 to 7 bits
  at the row start (= on the left edge), indicated by offset.
-----------------------------------------------------------------------------*/
    unsigned int const fullLength = cols + offset;

    unsigned int sum;

    if (fullLength <= 8) {
        /* All bits are in a single byte */
        sum = bitpop8((packedRow[0] << offset ) & (0xff << (8 - cols)));
    } else {
        unsigned int const colByteCnt  = pbm_packed_bytes(fullLength);
        unsigned int const fullByteCnt = fullLength/8;

        unsigned int i;

        /* First byte, whether it is full or not */
        sum = bitpop8(packedRow[0] << offset );

        /* Second byte to last full byte */
        for (i = 1; i < fullByteCnt; ++i)
            sum += bitpop8(packedRow[i]);

        /* Partial byte at the right end */
        if (colByteCnt > fullByteCnt)
            sum += bitpop8(packedRow[i] >> (8 - fullLength%8));
    }

    return sum;
}



bit
pbm_backgroundbitrow(unsigned const char * const packedBits,
                     unsigned int          const cols,
                     unsigned int          const offset) {
/*----------------------------------------------------------------------------
  PBM version of pnm_backgroundxelrow() with additional offset parameter.
  When offset == 0, produces the same return value as does
  pnm_backgroundxelrow(promoted_bitrow, cols, ...)
-----------------------------------------------------------------------------*/
    const unsigned char * const row = &packedBits[offset/8];
    unsigned int const rs = offset % 8;
    unsigned int const last = pbm_packed_bytes(cols + rs) - 1;

    unsigned int retval;

    bool const firstbit = (row[0] >> (7-rs)) & 0x01;
    bool const lastbit  = (row[last] >> (7- (cols+rs-1)%8)) & 0x01;

    if (firstbit == lastbit)
        retval = firstbit;
    else {
        if (bitpop(row, cols, rs) >= cols/2)
            retval = PBM_BLACK;
        else
            retval = PBM_WHITE;
    }
    return retval;
}



